An image scanner is a device having a light source and a color image sensor head for generating a digital representation of an image. The light source illuminates the image and the color image sensor head moves across the image field (or the image moves relative to the color image sensor head). The color image sensor head receives light reflected off the image and responsively generates digital image data. The digital image data includes values that correspond to intensity and/or other attributes of color components for each picture element (pixel) in the image.
The accuracy of an image scanner can be a measure of color differential between the original image and the colors represented by the digital image data generated by the color image sensor head. While some color image sensor head models perform well and provide accurate digital image data, some models do not. One example of color inaccuracy is digital image data having color component values that define a yellowish-orange color in areas where the original image is pure yellow.
Color correction techniques exist for adjusting the color component values in the digital image data. Some color correction techniques are implemented at the host computer that receives the digital image data from the scanner. Although color inaccuracies can be corrected at a host computer, the process of correcting the color at the host requires the implementation and use of a graphics editor or other application running on the host, which for many uses and/or users is undesirable or even unacceptable.
Other color correction techniques may be implemented in the scanner before outputting the digital image data. Scanner implemented color correction techniques include simple 3×3 multiplication matrices and full 3-D color space conversion algorithms and tables. 3×3 multiplication matrices are simplistic but in most cases provide nominal color correction. Full 3-D color space conversion techniques are comprehensive but the algorithms consume a lot of processing time and slow down the imaging process, which is usually sensed by the user. Also, implementing a 3-D color space conversion table in a scanner typically requires adding or upgrading a memory device and results in an increased cost of the scanner.